European patent application publication number EP-A1-0492485 discloses the compound 1-(4-aminophenyl)-3-acetyl-4-methyl-7,8-methylenedioxy-3,4-dihydro-5H-2,3- benzodiazepine. The compound is a potent and selective antagonist of the excitatory amino acid AMPA receptor and is believed to have the ability to treat a variety of neurological disorders. The (R)-enantiomer of this compound hereinafter referred to as (R)-7-acetyl-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxolo[4,5-h][ 2,3]benzodiazepine, is the most potent enantiomer.